Impacts of roads on individual wildlife genetics
by Karl Jarvis
Roads do a fantastic job of
connecting people, but they are also incredibly dangerous barriers to wildlife.
Two major consequence of roads for wildlife are 1) fragmentation, and 2)
roadkill. Fragmentation is a huge issue because roads divide up habitat,
preventing wildlife from moving to areas where they can access food, shelter,
and mates. Very few wild areas are left in the world that do not have roads or
other barriers in them. In addition,
collisions with vehicles cause large numbers of animal deaths. At least one
million large mammals are killed each year on US roads, and this number is
dramatically higher for smaller animals.
are a powerful tool for understanding the impacts of roads on wildlife.
Geneticists use DNA analyses to understand the impacts of fragmentation, and as
a result, we know that roads cause populations of many species to be
genetically divided. Animals on different sides of roads can become genetically
distinct in a matter of only a few generations. However, until now, genetics
has not been used to understand how roadkill impacts populations. We are
currently using genetics to understand how roadkill and fragmentation differ in
their effects on the genetics of wildlife.
Our main goal is to understand how roadkill and road
avoidance affect wildlife populations. Our main study animals are kangaroo rats
in the Sonoran desert of southern Arizona, whose populations are divided by
roads. These kangaroo rat populations are fragmented by roads and are also
prone to being killed on roads, so we hope to understand how these two factors
affect their genetic patterns. To get genetic samples from the kangaroo rats,
we capture them in live traps and take tiny snips from their ear tips. We get
genetic information from these tissue samples to understand levels of genetic
diversity across the populations. We are also using computer simulations to
model how different levels of roadkill and avoidance would affect genetic
patterns. By comparing simulations and actual genetics, we can understand what
patterns result from highways cutting through wild lands.
This study, together with analyses
of other wildlife species, such as the black bear, American pronghorn and the
alpine newt will provide an understanding of how roads with different
characteristics affect different species. The computer modeling approach will
allow us to develop predictions of the effects of roads on wildlife and improve
our ability to anticipate road effects. The results will allow us to understand
how we can best reduce the impacts of roads on wildlife.